Dr. Mario Online Rx features versions of the Nintendo DS title Brain Age 2's mini-games called Virus Buster and Germ Buster, which uses the pointer function of the Wii Remote to move pills, and allows up to four players to participate cooperatively.

The title supports the now defunct Nintendo Wi-Fi Connection service, which allowed players to compete with one another over the Internet.

A majority of features from previous installments, such as the virus and speed levels, are present in Dr. Mario Online Rx.

Whereas the original only had Easy, Normal, and Hard as options, this version allows to adjust virus level and music as well.

[5] IGN called the main game "timeless" and the new Virus Buster mode "chaotically awesome".

[16] GamePro said, "Playing Dr. Mario Online RX for an hour or so virtually guarantees a smile and good mood to follow.